<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html lang="en">
<head>
<title>Source code</title>
<link rel="stylesheet" type="text/css" href="../../../../../stylesheet.css" title="Style">
</head>
<body>
<div class="sourceContainer">
<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2011 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.base;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import static com.google.common.base.Preconditions.checkNotNull;<a name="line.19"></a>
<span class="sourceLineNo">020</span><a name="line.20"></a>
<span class="sourceLineNo">021</span>import com.google.common.annotations.Beta;<a name="line.21"></a>
<span class="sourceLineNo">022</span>import com.google.common.annotations.GwtCompatible;<a name="line.22"></a>
<span class="sourceLineNo">023</span>import com.google.common.annotations.GwtIncompatible;<a name="line.23"></a>
<span class="sourceLineNo">024</span><a name="line.24"></a>
<span class="sourceLineNo">025</span>import java.io.Serializable;<a name="line.25"></a>
<span class="sourceLineNo">026</span>import java.lang.reflect.Field;<a name="line.26"></a>
<span class="sourceLineNo">027</span><a name="line.27"></a>
<span class="sourceLineNo">028</span>import javax.annotation.Nullable;<a name="line.28"></a>
<span class="sourceLineNo">029</span><a name="line.29"></a>
<span class="sourceLineNo">030</span>/**<a name="line.30"></a>
<span class="sourceLineNo">031</span> * Utility methods for working with {@link Enum} instances.<a name="line.31"></a>
<span class="sourceLineNo">032</span> *<a name="line.32"></a>
<span class="sourceLineNo">033</span> * @author Steve McKay<a name="line.33"></a>
<span class="sourceLineNo">034</span> *<a name="line.34"></a>
<span class="sourceLineNo">035</span> * @since 9.0<a name="line.35"></a>
<span class="sourceLineNo">036</span> */<a name="line.36"></a>
<span class="sourceLineNo">037</span>@GwtCompatible(emulated = true)<a name="line.37"></a>
<span class="sourceLineNo">038</span>@Beta<a name="line.38"></a>
<span class="sourceLineNo">039</span>public final class Enums {<a name="line.39"></a>
<span class="sourceLineNo">040</span><a name="line.40"></a>
<span class="sourceLineNo">041</span>  private Enums() {}<a name="line.41"></a>
<span class="sourceLineNo">042</span><a name="line.42"></a>
<span class="sourceLineNo">043</span>  /**<a name="line.43"></a>
<span class="sourceLineNo">044</span>   * Returns the {@link Field} in which {@code enumValue} is defined.<a name="line.44"></a>
<span class="sourceLineNo">045</span>   * For example, to get the {@code Description} annotation on the {@code GOLF}<a name="line.45"></a>
<span class="sourceLineNo">046</span>   * constant of enum {@code Sport}, use<a name="line.46"></a>
<span class="sourceLineNo">047</span>   * {@code Enums.getField(Sport.GOLF).getAnnotation(Description.class)}.<a name="line.47"></a>
<span class="sourceLineNo">048</span>   *<a name="line.48"></a>
<span class="sourceLineNo">049</span>   * @since 12.0<a name="line.49"></a>
<span class="sourceLineNo">050</span>   */<a name="line.50"></a>
<span class="sourceLineNo">051</span>  @GwtIncompatible("reflection")<a name="line.51"></a>
<span class="sourceLineNo">052</span>  public static Field getField(Enum&lt;?&gt; enumValue) {<a name="line.52"></a>
<span class="sourceLineNo">053</span>    Class&lt;?&gt; clazz = enumValue.getDeclaringClass();<a name="line.53"></a>
<span class="sourceLineNo">054</span>    try {<a name="line.54"></a>
<span class="sourceLineNo">055</span>      return clazz.getDeclaredField(enumValue.name());<a name="line.55"></a>
<span class="sourceLineNo">056</span>    } catch (NoSuchFieldException impossible) {<a name="line.56"></a>
<span class="sourceLineNo">057</span>      throw new AssertionError(impossible);<a name="line.57"></a>
<span class="sourceLineNo">058</span>    }<a name="line.58"></a>
<span class="sourceLineNo">059</span>  }<a name="line.59"></a>
<span class="sourceLineNo">060</span><a name="line.60"></a>
<span class="sourceLineNo">061</span>  /**<a name="line.61"></a>
<span class="sourceLineNo">062</span>   * Returns a {@link Function} that maps an {@link Enum} name to the associated<a name="line.62"></a>
<span class="sourceLineNo">063</span>   * {@code Enum} constant. The {@code Function} will return {@code null} if the<a name="line.63"></a>
<span class="sourceLineNo">064</span>   * {@code Enum} constant does not exist.<a name="line.64"></a>
<span class="sourceLineNo">065</span>   *<a name="line.65"></a>
<span class="sourceLineNo">066</span>   * @param enumClass the {@link Class} of the {@code Enum} declaring the<a name="line.66"></a>
<span class="sourceLineNo">067</span>   *     constant values.<a name="line.67"></a>
<span class="sourceLineNo">068</span>   */<a name="line.68"></a>
<span class="sourceLineNo">069</span>  public static &lt;T extends Enum&lt;T&gt;&gt; Function&lt;String, T&gt; valueOfFunction(Class&lt;T&gt; enumClass) {<a name="line.69"></a>
<span class="sourceLineNo">070</span>    return new ValueOfFunction&lt;T&gt;(enumClass);<a name="line.70"></a>
<span class="sourceLineNo">071</span>  }<a name="line.71"></a>
<span class="sourceLineNo">072</span><a name="line.72"></a>
<span class="sourceLineNo">073</span>  /**<a name="line.73"></a>
<span class="sourceLineNo">074</span>   * A {@link Function} that maps an {@link Enum} name to the associated<a name="line.74"></a>
<span class="sourceLineNo">075</span>   * constant, or {@code null} if the constant does not exist.<a name="line.75"></a>
<span class="sourceLineNo">076</span>   */<a name="line.76"></a>
<span class="sourceLineNo">077</span>  private static final class ValueOfFunction&lt;T extends Enum&lt;T&gt;&gt;<a name="line.77"></a>
<span class="sourceLineNo">078</span>      implements Function&lt;String, T&gt;, Serializable {<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span>    private final Class&lt;T&gt; enumClass;<a name="line.80"></a>
<span class="sourceLineNo">081</span><a name="line.81"></a>
<span class="sourceLineNo">082</span>    private ValueOfFunction(Class&lt;T&gt; enumClass) {<a name="line.82"></a>
<span class="sourceLineNo">083</span>      this.enumClass = checkNotNull(enumClass);<a name="line.83"></a>
<span class="sourceLineNo">084</span>    }<a name="line.84"></a>
<span class="sourceLineNo">085</span><a name="line.85"></a>
<span class="sourceLineNo">086</span>    @Override<a name="line.86"></a>
<span class="sourceLineNo">087</span>    public T apply(String value) {<a name="line.87"></a>
<span class="sourceLineNo">088</span>      try {<a name="line.88"></a>
<span class="sourceLineNo">089</span>        return Enum.valueOf(enumClass, value);<a name="line.89"></a>
<span class="sourceLineNo">090</span>      } catch (IllegalArgumentException e) {<a name="line.90"></a>
<span class="sourceLineNo">091</span>        return null;<a name="line.91"></a>
<span class="sourceLineNo">092</span>      }<a name="line.92"></a>
<span class="sourceLineNo">093</span>    }<a name="line.93"></a>
<span class="sourceLineNo">094</span><a name="line.94"></a>
<span class="sourceLineNo">095</span>    @Override public boolean equals(@Nullable Object obj) {<a name="line.95"></a>
<span class="sourceLineNo">096</span>      return obj instanceof ValueOfFunction &amp;&amp;<a name="line.96"></a>
<span class="sourceLineNo">097</span>          enumClass.equals(((ValueOfFunction) obj).enumClass);<a name="line.97"></a>
<span class="sourceLineNo">098</span>    }<a name="line.98"></a>
<span class="sourceLineNo">099</span><a name="line.99"></a>
<span class="sourceLineNo">100</span>    @Override public int hashCode() {<a name="line.100"></a>
<span class="sourceLineNo">101</span>      return enumClass.hashCode();<a name="line.101"></a>
<span class="sourceLineNo">102</span>    }<a name="line.102"></a>
<span class="sourceLineNo">103</span><a name="line.103"></a>
<span class="sourceLineNo">104</span>    @Override public String toString() {<a name="line.104"></a>
<span class="sourceLineNo">105</span>      return "Enums.valueOf(" + enumClass + ")";<a name="line.105"></a>
<span class="sourceLineNo">106</span>    }<a name="line.106"></a>
<span class="sourceLineNo">107</span><a name="line.107"></a>
<span class="sourceLineNo">108</span>    private static final long serialVersionUID = 0;<a name="line.108"></a>
<span class="sourceLineNo">109</span>  }<a name="line.109"></a>
<span class="sourceLineNo">110</span><a name="line.110"></a>
<span class="sourceLineNo">111</span>  /**<a name="line.111"></a>
<span class="sourceLineNo">112</span>   * Returns an optional enum constant for the given type, using {@link Enum#valueOf}. If the<a name="line.112"></a>
<span class="sourceLineNo">113</span>   * constant does not exist, {@link Optional#absent} is returned. A common use case is for parsing<a name="line.113"></a>
<span class="sourceLineNo">114</span>   * user input or falling back to a default enum constant. For example,<a name="line.114"></a>
<span class="sourceLineNo">115</span>   * {@code Enums.getIfPresent(Country.class, countryInput).or(Country.DEFAULT);}<a name="line.115"></a>
<span class="sourceLineNo">116</span>   *<a name="line.116"></a>
<span class="sourceLineNo">117</span>   * @since 12.0<a name="line.117"></a>
<span class="sourceLineNo">118</span>   */<a name="line.118"></a>
<span class="sourceLineNo">119</span>  public static &lt;T extends Enum&lt;T&gt;&gt; Optional&lt;T&gt; getIfPresent(Class&lt;T&gt; enumClass, String value) {<a name="line.119"></a>
<span class="sourceLineNo">120</span>    checkNotNull(enumClass);<a name="line.120"></a>
<span class="sourceLineNo">121</span>    checkNotNull(value);<a name="line.121"></a>
<span class="sourceLineNo">122</span>    try {<a name="line.122"></a>
<span class="sourceLineNo">123</span>      return Optional.of(Enum.valueOf(enumClass, value));<a name="line.123"></a>
<span class="sourceLineNo">124</span>    } catch (IllegalArgumentException iae) {<a name="line.124"></a>
<span class="sourceLineNo">125</span>      return Optional.absent();<a name="line.125"></a>
<span class="sourceLineNo">126</span>    }<a name="line.126"></a>
<span class="sourceLineNo">127</span>  }<a name="line.127"></a>
<span class="sourceLineNo">128</span>}<a name="line.128"></a>




























































</pre>
</div>
</body>
</html>
